Function gf256_word_complexity 

pub fn gf256_word_complexity(data: &[u8]) -> usize

The GF(2⁸) word linear complexity of a byte string — the length of the shortest byte-oriented (GF(256)) LFSR that generates it, via Berlekamp–Massey over the AES field. The word analogue of the bit linear complexity: low relative to n/2 ⇒ a word-LFSR keystream, a certified weakness. (Runs in O(n²) byte-ops — 64× fewer than the bit-level BM on the same data.)